Solid state laser apparatus incorporate laser rods within a cavity as the active lasing medium. The laser rods receive pumping energy, for example from diode arrays, and are subject to heat build up. One of the primary design considerations of a solid state laser is how to cool the laser rod. The more effectively that the cooling can be accomplished, the more power that can be generated by the laser.
In presently known technology, in order to cool the laser rod, a cooling fluid is contained in a reservoir which is located around the laser rod. It is desirable to maximize the cooling effect between the laser rod and the cooling fluid. The prior technique to accomplish this is to provide a maximum outer periphery of the laser rod. Since the outer periphery cannot be increased much past standard configurations without affecting operation of the laser, the maximum cooling efficiency of the laser rods cannot be increased extensively past values using presently available laser techniques and laser rod/cooling flow configurations.
Present techniques of cooling the rod consist of applying the coolant liquid over the surface of the rod so that it flows in a direction parallel to the longitudinal axis of the rod. This cooling technique is referred to as axial flow cooling.
One known technique which provides for effective pumping of lasers is to encase the laser rod within a material which is transparent to the photonic radiation which is being used to pump the laser rod. This laser configuration is illustrated in U.S. Pat. No. 4,969,155 entitled "Integrating Laser Diode Pumped Laser Application", which issued on Nov. 6, 1990 to O. Kahan. In FIG. 3 of the Kahan patent an apparatus is shown wherein cooling fluid with axial flow is used to surround the laser rod.